TNG, page-2

This article is four years old
http://www.energyandcapital.com/articles/the-best-thing-since-lithium/1531

Vanadium demand for batteries is expected to grow 30% in the next three years. And supply is already struggling to keep up. In fact demand is expected to outpace it by next year.
This is because up to 90% of the vanadium on the market isn't suitable for batteries. It comes from ferrovanadium, and is only suitable as strengthening alloy for steel.
The good stuff comes from vanadium pentoxide... and only a few companies have access to it.

Pressure cooker is building- How much Pentoxide do we have?